Here in New York City ductless split heat pumps are more and more popular because there is no space for ducts in old buildings or new expensive real estate. Many of us are too smart to install ducts (except, of course, for ventilation only). We use ductless splits for cooling and sometimes for heating. Ductless splits have many advantages, but a big disadvantage is most people interpret the plumbing code to require condensate be piped to an indirect waste.
For apartments or hotels this means a drain running the height of the building with a P- trap at each connection, which dries out for more than half the year when there is no cooling. As the waste stack is piped indirect, there is no problem with sewer gases entering living spaces. The only things that enter living spaces through the drain stack are cockroaches, fleas, noise, smoke from cigarettes and whatever else someone might smoke, smoke from a fire and air. These drains probably violate fire codes requiring smoke-tight partitions, but nobody ever seems to worry about that.